Lec 01 basic concepts

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1. Basic Concepts Computer Organization and Assembly Language 2. Outline Welcome to COAL Assembly-, Machine-, and High-Level Languages Assembly Language Programming Tools Programmers View of a Computer System Basic Computer Organization 3. Welcome to COAL Assembly language programming Basics of computer organization CPU design Software Tools Microsoft Macro Assembler (MASM) version 6.15 Link Libraries provided by Author (Irvine32.lib and Irivine16.lib) OR VS2010 Express 4. Textbook Kip Irvine: Assembly Language for Intel-Based Computers or X86 Processors 5th edition (2007) 5. Course Objectives After successfully completing the course, students will be able to: Describe the basic components of a computer system, its instruction set architecture and its basic fetch-execute cycle operation. Describe how data is represented in a computer and recognize when overflow occurs. Recognize the basics of assembly language programming including addressing modes. Analyze, design, implement, and test assembly language programs. 6. Required Background The student should already be able to program confidently in at least one high-level programming language, such as Java or C. Prerequisite DLD Introduction to computing 7. Next Welcome to COAL Assembly-, Machine-, and High-Level Languages Assembly Language Programming Tools Programmers View of a Computer System Basic Computer Organization 8. Some Important Questions to Ask What is Assembly Language? Why Learn Assembly Language? What is Machine Language? How is Assembly related to Machine Language? What is an Assembler? How is Assembly related to High-Level Language? Is Assembly Language portable? 9. A Hierarchy of Languages 10. Assembly and Machine Language Machine language Native to a processor: executed directly by hardware Instructions consist of binary code: 1s and 0s Assembly language A programming language that uses symbolic names to represent operations, registers and memory locations.Slightly higher-level language Readability of instructions is better than machine language One-to-one correspondence with machine language instructions Assemblers translate assembly to machine code Compilers translate high-level programs to machine code Either directly, or Indirectly via an assembler 11. Compiler and Assembler 12. Instructions and Machine LanguageEach command of a program is called aninstruction (it instructs the computer what to do).Computers only deal with binary data, hence the instructions must be in binary format (0s and 1s) . The set of all instructions (in binary form) makes up the computer'smachine language . This is also referred to as theinstruction set . 13. Instruction Fields Machine language instructions usually are made up of several fields. Each field specifies different information for the computer. The major two fields are:Opcodefield which stands for operation code and it specifies the particular operation that is to be performed.Each operation has its unique opcode.Operands fields which specify where to get the source and destination operands for the operation specified by the opcode.The source/destination of operands can be a constant, the memory or one of the general-purpose registers. 14. Assembly vs. Machine Code 15. Translating Languages English:D is assigned the sum of A times B plus 10. High-Level Language:D = A * B + 10 Intel Assembly Language: mov eax, A mul B add eax, 10 mov D, eax Intel Machine Language: A1 00404000 F7 25 00404004 83 C0 0A A3 00404008 A statement in a high-level language is translated typically into several machine-level instructions 16. Mapping Between Assembly Language and HLL Translating HLL programs to machine language programs is not a one-to-one mappingA HLL instruction (usually called a statement) will be translated to one or more machine language instructions 17. Advantages of High-Level Languages Program development is faster High-level statements: fewer instructions to code Program maintenance is easier For the same above reasons Programs are portable Contain few machine-dependent details Can be used with little or no modifications on different machines Compiler translates to the target machine language However, Assembly language programs are not portable 18. Why Learn Assembly Language? Accessibility to system hardware Assembly Language is useful for implementing system software Also useful for small embedded system applications Space and Time efficiency Understanding sources of program inefficiency Tuning program performance Writing compact code Writing assembly programs gives the computer designer the needed deep understanding of the instruction set and how to design oneTo be able to write compilers for HLLs, we need to be expert with the machine language. Assembly programming provides this experience 19. Assembly vs. High-Level Languages Some representative types of applications: 20. Next Welcome to COAL Assembly-, Machine-, and High-Level Languages Assembly Language Programming Tools Programmers View of a Computer System Basic Computer Organization 21. Assembler Software tools are needed for editing, assembling, linking, and debugging assembly language programs Anassembleris a program that convertssource-codeprograms written inassembly languageintoobject filesinmachine language Popular assemblers have emerged over the years for the Intel family of processors. These include TASM (Turbo Assembler from Borland) NASM (Netwide Assembler for both Windows and Linux), and GNU assembler distributed by the free software foundation We will useMASM(Macro Assembler from Microsoft) 22. Linker and Link Libraries You need a linker program to produce executable files It combines your program'sobject file created by the assembler with other object files andlink libraries , and produces a singleexecutable program LINK32.EXEis the linker program provided with the MASM distribution for linking 32-bit programs We will also use a link library for input and output CalledIrvine32.libdeveloped by Kip Irvine Works in Win32 console mode under MS-Windows 23. Assemble and Link Process A project may consist of multiple source files Assembler translates each source file separately into an object file Linker links all object files together with link libraries Source File Source File Source File Assembler Object File Assembler Object File Assembler Object File Linker Executable File Link Libraries 24. Debugger Allows you to trace the execution of a program Allows you to view code, memory, registers, etc. We will use the Debug,32-bit Windows debugger or VS2010 built in Debugger 25. Editor Allows you to create assembly language source filesSome editors provide syntax highlighting features and can be customized as a programming environment 26. Next Welcome to COE 205 Assembly-, Machine-, and High-Level Languages Assembly Language Programming Tools Programmers View of a Computer System Basic Computer Organization 27. Programmers View of a Computer System Increased level of abstraction Each level hides the details of the level below it Application Programs High-Level Language Assembly Language Operating System Instruction Set Architecture Microarchitecture Digital Logic Level 0 Level 1 Level 2 Level 3 Level 4 Level 5 28. Programmer's View 2 Application Programs (Level 5) Written in high-level programming languages Such as Java, C++, Pascal, Visual Basic . . . Programs compile into assembly language level (Level 4) Assembly Language (Level 4) Instruction mnemonics are used Have one-to-one correspondence to machine language Calls functions written at the operating system level (Level 3) Programs are translated into machine language (Level 2) Operating System (Level 3) Provides services to level 4 and 5 programs Translated to run at the machine instruction level (Level 2) 29. Programmer's View 3 Instruction Set Architecture (Level 2) Specifies how a processor functions Machine instructions, registers, and memory are exposed Machine language is executed by Level 1 (microarchitecture) Microarchitecture (Level 1) Controls the execution of machine instructions (Level 2) Implemented by digital logic (Level 0) Digital Logic (Level 0) Implements the microarchitecture Uses digital logic gates Logic gates are implemented using transistors 30. Instruction Set Architecture (ISA) Collection of assembly/machine instruction set of the machineMachine resources that can be managed with these instructions MemoryProgrammer-accessible registers. Provides a hardware/software interface 31. Instruction Set Architecture (ISA) 32. Next Welcome to COAL Assembly-, Machine-, and High-Level Languages Assembly Language Programming Tools Programmers View of a Computer System Basic Computer Organization 33. Basic Computer Organization Since the 1940's, computers have 3 classic components: Processor, called also the CPU (Central Processing Unit) Memory and Storage Devices I/O Devices Interconnected with one or more buses Bus consists of Data Bus Address Bus Control Bus Processor (CPU) Memory registers ALU clock I/O Device #1 I/O Device #2 data bus control bus address bus CU 34. Processor (CPU) Processor consists of Datapath ALU Registers Control unit ALU Performs arithmeticand logic instructions Control unit (CU) Generates the control signals required to execute instructions Implementation varies from one processor to another 35. Synchronizes Processor and Bus operations Clock cycle = Clock period = 1 / Clock rate Clock rate = Clock frequency = Cycles per second 1 Hz = 1 cycle/sec 1 KHz = 10 3cycles/sec 1 MHz = 10 6cycles/sec 1 GHz = 10 9cycles/sec 2 GHz clock has a cycle time = 1/(210 9 ) = 0.5 nanosecond (ns) Clock cycles measure the execution of instructions Clock Cycle 1 Cycle 2 Cycle 3 36. Memory Ordered sequence of bytes The sequence number is called thememory address Byte addressable memory Each byte has a unique address Supported by almost all processors Physical address space Determined by the address bus width Pentium has a 32-bit address bus Physical address space =4GB = 2 32bytes Itanium with a 64-bit address bus can support Up to2 64bytesof physical address space 37. Address Space Address Space is the set of memory locations (bytes) that can be addressed 38. CPU Memory Interface Address BusMemory address is put on address bus If memory address =mbits then 2 mlocations are addressed Data Bus: b-bit bi-directional bus Data can be transferred in both directions on the data bus Note that b is not necessary equal to w or s. So data transfers might take more than a single cycle (if w > b) . Control Bus Signals control transfer of data Read request Write request Complete transfer 39. Memory Devices Random-Access Memory (RAM) Usually called the main memoryIt can be read and written toIt does not store information permanently (Volatile , when it is powered off, the stored information are gone)Information stored in it can be accessed in any order at equal time periods (hence the name random access)Information is accessed by an address that specifies the exact location of the piece of information in the RAM.DRAM = Dynamic RAM 1-Transistor cell + trench capacitor Dense but slow, must be refreshed Typical choice for main memory SRAM: Static RAM 6-Transistor cell, faster but less dense than DRAM Typical choice for cache memory 40. Memory Devices ROM (Read-Only-Memory) A read-only-memory, non-volatile i.e. stores information permanentlyHas random access of stored informationUsed to store the information required to startup the computer Many types: ROM, EPROM, EEPROM, and FLASH FLASH memory can be erased electrically in blocks Cache A very fast type of RAM that is used to store information that is most frequently or recently used by the computerRecent computers have 2-levels of cache; the first level is faster but smaller in size (usually called internal cache), and the second level is slower but larger in size (external cache). 41. Processor-Memory Performance Gap 1980 No cache in microprocessor 1995 Two-level cache on microprocessor CPU: 55% per year DRAM: 7% per year 1 10 100 1000 1980 1981 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 1982 Processor-Memory Performance Gap: (grows 50% per year) Performance Moores Law 42. The Need for a Memory Hierarchy Widening speed gap between CPU and main memory Processor operation takes less than 1 ns Main memory requires more than 50 ns to access Each instruction involves at least one memory access One memory access to fetch the instruction Additionalmemory accesses for instructions involving memory data access Memory bandwidth limits the instruction execution rate Cache memory can help bridge the CPU-memory gap Cache memory is small in size but fast 43. Typical Memory Hierarchy Registers are at the top of the hierarchy Typical size < 1 KB Access time < 0.5 ns Level 1 Cache (8 64 KB) Access time: 0.5 1 ns L2 Cache (512KB 8MB) Access time: 2 10 ns Main Memory (1 2 GB) Access time: 50 70 ns Disk Storage (> 200 GB) Access time: milliseconds Microprocessor Registers L1 Cache L2 Cache Memory Disk, Tape, etc Memory Bus I/O Bus Faster Bigger 44. Magnetic Disk Storage Disk Access Time =Seek Time+Rotation Latency+Transfer Time Seek Time : head movement to the desired track (milliseconds) Rotation Latency : disk rotation until desired sector arrives under the head Transfer Time : to transfer data Track 0 Track 1 Sector Recording area Spindle Direction of rotation Platter Read/write head Actuator Arm Track 2 45. Example on Disk Access Time Given a magnetic disk with the following properties Rotation speed = 7200 RPM (rotations per minute) Average seek = 8 ms, Sector = 512 bytes, Track = 200 sectors Calculate Time of one rotation (in milliseconds) Average time to access a block of 32 consecutive sectors Answer Rotations per second Rotation time in milliseconds Average rotational latency Time to transfer 32 sectors 200 sectors transferred =8.33 ms Average access time = 7200/60 = 120 RPS = 1000/120 = 8.33 ms = time of half rotation = 4.17 ms = (32/200) * 8.33 = 1.33 ms = 8 + 4.17 + 1.33 = 13.5 ms